Of the many thousands of participants at the Bonn climate conference which begins on 6 November, there will arguably be none who come with as much hope, courage and anger as the busload of indigenous leaders who have been criss-crossing Europe over the past two weeks, on their way to the former German capital.

The 20 activists on the tour represent forest communities that have been marginalised over centuries but are now increasingly recognised as important actors against climate change through their protection of carbon sinks.

In the run-up to the United Nations talks, they have been visiting the UK, France, Belgium, the Netherlands and Germany, talking to city leaders, environment NGOs and youth groups. Their aim is to build support for their role as forest defenders – a role that frequently puts them odds with agribusiness, mining companies and public security. The Observer caught up with them on the road to Paris.

“We have been looking after the forest for thousands of years. We know how to protect them,” said Candida Dereck Jackson, vice president of the National Indigenous Alliance in Honduras, as she outlined the principal demands of the group: respect for land rights, recognition of crimes against the environment, direct negotiations over forest protection, decriminalisation of indigenous activists, and free, prior and informed consent before any development by outsiders.

In one sense it is part of a battle that first peoples – as many indigenous groups refer to themselves – have been fighting since their territories were colonised hundreds of years ago. But this time the campaign is being waged from a bus – previously used for rock music tours and election campaigns – in the context of growing concern about the climate and environment.

This has provided some overlap with their ancient struggle to retain ancestral land and a different set of values.

Cándido Mezúa of the Mesoamerican Alliance of Peoples and Forests said priorities needed to shift away from outside companies who were threatening forests and towards native communities that supported them.

“We see with great sadness that billions of dollars are invested in agribusiness and the institutions that are behind the crisis we are facing, but there is very little interest in indigenous populations who can help with a solution,” he said at a stop at the Royal Society in London.

This is not just a moral argument. Researchers at the World Resources Institute have found that tenure-secure indigenous forestlands provided significant global carbon benefits. In Bolivia, Brazil and Colombia alone they say this is worth $25bn–$34bn over the next 20 years – equivalent to taking between nine million and 12.6 million passenger vehicles off the roads for a year.

Alain Frechette of the Rights and Resources Institute said this was the most cost-effective way to reduce emissions. “Community-owned land sequesters more carbon, has lower levels of deforestation, greater biodiversity and supports more people than public or privately owned forest,” he told the gathering of indigenous leaders, supporters and journalists.

The contrast with more expensive solutions was apparent at the same venue the previous evening when oil company executives and senior politicians called for hundreds of billions of dollars of spending on carbon capture and storage technology, which – though important – is expected to contribute only 14% of the emissions cuts needed for the 2C target.

Instead of such huge sums, participants in the indigenous caravan say they could contribute more to the fight against climate change if their land rights were recognised and states accepted the concept of crimes against the environment. “Money is not important for indigenous people. What we want, frankly, is for you to leave us alone,” said Mina Setra of the Indigenous Peoples’ Alliance of the Archipelago. “We don’t want to be criminalised for protecting our land.”